Thermal-process vessels used in oil refineries and other petrochemical and chemical process facilities have highly abrasive and high-temperature environments. To protect the vessel shells (e.g., sidewalls), their internal surface is typically lined with a refractory material such as a thin layer of concrete. To secure the refractory material in place, anchoring devices and systems have been developed.
The most common form of thin-layer abrasion-resistant refractory concrete anchoring system is called HEXMESH (aka “hexmetal” or just “hex”) anchor sheets. Hex includes a series of steel strips that are interlocked (i.e., “clinched” together by a tab-and-slot arrangement) to form a sheet or mat of hexagonal cells in a honeycomb-patterned array or grid. The hex sheets are installed by fitting (bending/shaping and cutting/sizing) them to whatever vessel shape and size is to be lined, and then welding them in place by a large number of welds to create a strong attachment to the underlying vessel shell. Once welded, mixed refractory concrete is then rammed, beaten, or packed into the hex cells. The refractory concrete and hex sheet together form a barrier system that protects the underlying vessel shell from heat, abrasion, and chemical attack.
Over the decades that hex has been in use, several weaknesses in this system have been exposed. The hex and refractory system must move in concert with any flex that occurs in the vessel shell because the hex sheet is fitted and welded flush with and rigidly to the vessel shell. This makes the hex and refractory system prone to “biscuiting,” which means individual hex cells will tend to “pop” the refractory concrete out in a hexagonal biscuit shape when the vessel shell experiences thermal expansion or contraction. In addition, this can compromise the protective capabilities of the refractory concrete liner by opening gaps that allow catalysts, gases, carbon, and other process-related materials to contact the exposed portion of the vessel shell. This in turn can lead to further failure of the refractory concrete liner system and the need for premature replacement of extremely expensive process vessels and components. Furthermore, installing hex is very time-consuming, tedious, and cumbersome because of the large number of welds required and because the sheets must be cut on-site to custom-fit each vessel, beat into shape and place with a hammer, and sometimes cut into small pieces to fit through access openings to the work areas, with this being particularly an issue for irregularly shaped vessels.
Other refractory anchoring devices and systems include D-BAR anchors (e.g., U.S. Pat. No. 6,393,789), C-BAR anchors, and G3 anchors. Some of these are provided in sheet form and thus must by bent and cut to fit the individual vessel in the same manner as the HEXMESH sheets. And some of these include multiple parts that are interlocked together with a clinching system in the same manner as the HEXMESH sheets. As such, these other refractory anchoring devices and systems include some or all of the same drawbacks.
Accordingly, it can be seen that needs exist for improvements in anchoring devices, systems, and methods for refractory liners for thermal vessels. It is to the provision of solutions to these and other problems that the present invention is primarily directed.